Your symptoms pain in back region is not sufficient. Moreover x- ray spine AP view is also not sufficient to diagnose condition. In your age group most commonly back pain is postural . Need more history before comment. Lumbosacral strain that causes back pain related to posture , lifting heavy weight, Doing gym without good trainer, sometimes infection and sometimes tumor which is rare in your age group. You can use muscle relaxant with or without pain killer for your symptoms but for knowing true cause you can consult online regarding history and investigations.

Avoid bending and do back exercises.